This invention relates to a method and system for patching at least one original on an input drum of a plate-making scanner or an original-patching sheet to be mounted on the input drum, and also to a method and system for determining the location of a trimming frame, which corresponds to a desired region located in the original and to be scanned by the scanner, on the input drum or the original-patching sheet to be mounted on the input drum.
When making a printing plate, it is often necessary to trim an image of a major or minor portion of an original, which is composed of one or more sheets of pictures or the like, by designating the size and shape of the image and then to patch the image at a desired location and angle in accordance with a designated layout so as to form an assembled image.
A layout scanner is provided with the ability to rotate, each input image. However, the resolution of the image is reduced when it is rotated. Moreover, most scanners are not equipped with an image-rotating function. When placing an original on a scanning drum, it is therefore desireable to patch the original at a desired angle and then to subject same to photoelectric scanning.
As a method for patching an original on an input drum (which may also be called cylinder) of a scanner at a desired angle, reference may be made to Japanese Patent Laid-Open (Kokai) No. 55-21033.
According to the method disclosed in the above referred-to Japanese patent publication, an image of an original is projected on a layout sheet on which a designated layout has been drawn in advance. The magnification of the image is adjusted and the layout sheet is shifted so that a desired duplicate region of the projected image of the original is fit in both size and angle in a trimming frame on the layout sheet which trimming frame has been designated for the image of the original. A reference line corresponding to the inclination of the layout sheet at that time is marked in a margin of the original or on an auxiliary tab attached to the original. By bringing a line located horizontally on the input drum and the reference line on the original into registration when patching the original onto the input drum, the original can be patched at the desired angle.
The above method has, however, several drawbacks. It requires an additional step of drawing the reference line on the original and it is difficult to patch the original accurately at the desired angle because the original is patched by eye measurement relying upon a short reference line.
With a view toward solving the above drawbacks, the present applicant has disclosed in Japanese Patent Laid-Open (Kokai) No. 59-197040 a method for patching an original accurately on an input drum without the need for drawing a reference line on the original.
Even with the above-mentioned improved method, it is still difficult to determine the accurate location of a trimming frame for an original on an input drum.
An object of this invention is therefore to provide a method and system for patching at least one original at a desired angle on an input drum of a scanner or an original-patching sheet to be mounted on the input drum in accordance with a layout sheet and for determining the location of a trimming frame for the original, which trimming frame corresponds to a desired scanning region of the original, with high accuracy.
In one aspect of this invention, there is thus provided a method for patching an original and extracting original-trimming data in a scanner, said method comprising the steps of:
mounting a layout sheet on a digitizer;
utilizing the digitizer to determine location data concerning trimming frames for each of at least one pattern located on a layout sheet and location data of a rectangular region circumscribing the trimming frame and corresponding to an area to be trimmed, storing these location data in a memory device, and reading out the location data of the trimming frame for the pattern from the memory device and displaying trimming lines for the pattern on a monitor;
picking up an original by means of a pick-up device, adjusting the angle, location and pick-up magnification of the original so as to display a desired duplicate portion of the original in such a way that the desired duplicate portion is fit in the trimming frame for the pattern;
calculating the location data of the rectangular region, which corresponds to the trimmed area of the original, on the original from the location data of the rectangular region corresponding to the trimmed area of the original and the pick-up magnification, shifting the original by means of an original-holding plate from the pick-up location thereof while maintaining the angle and patching the original on an input drum of the scanner or an original-patching sheet mounted on the input drum, and calculating the location data of the rectangular region, which corresponds to the trimmed area of the original, on the input drum from the distance of displacement of the original-holding plate and the location data of the rectangular region of the original, which region corresponds to the trimmed area of the original, on the original.
In another aspect of this invention, there is also provided a system for patching an original and extracting original-trimming data in a scanner, which comprises:
a digitizer for determining location data of a trimming frame for at least one pattern on a layout sheet, location data of a rectangular region circumscribing the trimming frame and corresponding to an area to be trimmed and data specifying the location of the rectangular region corresponding to the area to be trimmed;
a memory device for storing these location data;
an original-holding plate for holding an original at a desired angle and position;
a pick-up device for picking up the original with a desired magnification;
a monitor for displaying a desired duplicate portion of the image of the original, which image has been picked up by the pick-up device, in the trimming frame for the pattern which frame has been read out from the memory device;
an original-shifting device for shifting the original from the pick-up position by the pick-up device to an input drum of the scanner or an original-patching sheet mounted on the input drum while maintaining the desired angle; and
means for detecting the distance of displacement of the original-shifting device.
According to the present invention, upon patching one or more originals directly on an input drum of a scanner or on an original-patching sheet, the originals can respectively be patched at desired angles in accordance with a layout sheet without need for adding of reference points or lines on the originals. Moreover, it is also possible to obtain, with ease, accurate information on the locations of rectangular trimming regions, which correspond to desired scanning portions of the respective originals, and accurate information on the output locations.